I tried doing daily riding at ~10 miles but it was wearing me downmy legs were always sore, lately I've been doing 3-4 days/week. I'm still just getting into my routine over the last few months. I don't have time to do long rides during the week so I concentrate on getting my 10-12 mile rides done in faster times. When I first put my cyclocross bike together in early June I think I was at a 14.5 mph average speed lately I've been able to hang at 16.5 mph over a 12 mile ride. On a 20 miler I'm down around slightly over 14mph with no rest stops.

I've found that trying to push my limits at the lower mileage makes the longer rides easier. My toughest ride was a 23 mile ride that went from 200' MSL to 1000' MSL in 8 miles but from 400 to 1000 was only over about 3 or 4 miles that was TOUGH! I'm sure if I keep up my riding and loose so more weight I'll find that laughable but at this early stage it was hard, but 3 months ago I wouldn't have been able to make it!

I pretty much ride everyday year round (I'm a commuter). If you are trying to lose weight while cycling you can try to do more miles, or ride the same amount of miles more intensely (i.e. in a shorter amount of time). Also factor in your diet and recovery time and hopefully you will notice a difference in weight loss.

Sometimes the scale is not the best option for gauging weight loss. You have fluctuations in weight (not by much) daily. Try weighing yourself once a week or once every two weeks. See if your clothes are fitting differently or people start commenting on how you are looking. Take a picture one week, then another one the next week and so forth. Visually you might be changing, yet the scale is saying you only lost a few pounds.

Why 50lbs? Are you entering a competition that has weight divisions? Or do you think that losing 50lbs will make you look and feel differently? If its the former how long do you have that you need to lose that weight by? If its the latter then visual cues would be more helpful. Granted a concrete goal of a certain amount within a certain time period will help tremendously in your efforts.